Search Results (129)

Background/Objectives: The uprighting of mesially tipped mandibular second molars following first molar loss is a complex surgical and orthodontic challenge. Conventional methods often result in reciprocal anchorage loss. Mini-implants (MIs) have emerged as essential temporary anchorage devices (TADs) that provide absolute anchorage and enable more predictable tooth movements. Methods: Numerical simulations were performed to evaluate the forces required for mandibular second molar uprighting under two conditions: first, only with the second molar present, and second, with both the second and the third molars present. Although the periodontal ligament exhibits nonlinear and viscoelastic behavior in vivo, a linear elastic approximation was adopted to allow for a reliable evaluation of comparative stress distribution and initial displacement patterns within the scope of this exploratory biomechanical study. Stress distribution in the roots, periodontal ligament, and alveolar bone was assessed for each scenario. Two three-dimensional (3D) models of the left mandibular segment were created from scans of a human mandible and its teeth. The first model included the canine, the first and second premolars, and the second molar. A second model additionally incorporated the third molar. A retromolar MI was placed in both models. Molar uprighting was simulated using a spring connecting the implant to a button bonded on the mesial surface of the second molar. A force of 200 g was applied because in clinical orthodontic practice, forces that exceed approximately 2 N may cause pain or undesirable tooth mobility. Displacements along the X, Y, and Z axes, as well as regions of peak stress, were analyzed. Results: Model 1 showed maximum displacements at the furcation/mid-root, distal root apex, and distal crown, with von Mises stresses of 0.470 to 0.371 MPa. In Model 2, peak displacements occurred at the mesial root and crown, with stresses of 0.185 and 0.149 MPa, respectively. The magnitude of displacements was in the order of 10⁻⁵ mm. Such values represent initial mechanical responses rather than clinically observable tooth movements. However, the differences between models (e.g., the stress reduction) are expected to be clinically meaningful. Conclusions: Since clinical measurements regarding the stress distribution on teeth and surrounding tissues during orthodontic molar uprighting movements are impossible to perform, the finite element method (FEM) can offer insight into these aspects. The presence of the third molar significantly modulates the biomechanics of second molar uprighting via retromolar MIs. When the third molar is present, the second molar exhibits a reduced tendency for deformation during distalization, although this leads to a slower displacement. This FEM provides biomechanical insights but does not support direct clinical decision-making. The present findings should be viewed as theoretical biomechanical tendencies that require confirmation through clinical, experimental, and longitudinal studies before translation into clinical practice. Full article

Background/Objectives: Parkinson’s disease (PD) is a progressive neurodegenerative disorder that affects both motor and non-motor functioning, leading to increasing dependency and long-term psychosocial consequences. As the disease progresses, partners often assume caregiving roles, resulting in shifts in responsibilities, communication patterns, and emotional dynamics within marital relationships. The aim of this study was therefore to explore the impact of Parkinson’s disease on marital relationships. Methods: A qualitative interview study with a retrospective design was conducted. Six couples were recruited through a movement disorders clinic and a lay organization in Sweden. Semi-structured, face-to-face interviews were conducted separately with each partner. Interviews were transcribed verbatim and analyzed using conventional content analysis with an inductive design. Results: Four main themes emerged: managing the disease together in partnership, nurturing the relationship, facing marital hardship, and planning an uncertain future. Couples who adopted a positive and pragmatic outlook, shared responsibilities, and maintained open communication seemed to be better able to manage the disease. Engaging in joint activities and reciprocal communication strengthened emotional closeness. In contrast, changes in roles, emotional distress, loss of intimacy, and communication avoidance challenged relationships. Thinking about the future evoked feelings of ambivalence, as couples balanced uncertainty with a need for security. Conclusions: Parkinson’s disease affects marital relationships, reshaping roles, emotional bonds, and future perspectives. The ability of nurses to address both partners’ needs and promote communication and shared coping strategies is essential to strengthening couples’ well-being. Full article

Exogenous shocks can affect equity markets by changing volatility and cross-market co-movement. This study examines how two U.S.-centred events, treated as different shock types, influence time-varying conditional correlations between the U.S. stock market and other G7 markets. The uncertainty shock is proxied by the U.S. presidential election of 5 November 2024, while the action shock is proxied by President Trump’s 2 April 2025 announcement of reciprocal tariffs. Using daily log returns for the S&P 500 and leading indices for Canada, France, Germany, Italy, Japan and the United Kingdom, we cover January 2010 to July 2025 and assess event effects using correlation paths for June 2024–June 2025 and symmetric ±30-day windows. We employ a DCC-GARCH model to jointly estimate conditional variances and dynamic correlations for six USA-G7 pairs. The results indicate persistent correlation dynamics, with Canada/USA the highest and Japan/USA the lowest. Election-related uncertainty is associated with declines in correlation for European pairs, suggesting temporary decoupling, while Canada and Japan show only small changes. By contrast, the tariff action shock significantly increases conditional correlations across all country/USA pairs, implying stronger market synchronisation, with the largest increases in North America and parts of Europe, and the smallest adjustment in Japan. Full article

A two-degree-of-freedom, self-exciting pneumatic vibroactuator was investigated. The feature of this vibroactuator is that, along with the sliding-reciprocating movement of the working body along the axis, it also rotates about this axis. A new mathematical model of this vibroactuator is presented and solved using numerical methods. Comparisons of the results of numerical and experimental studies are described. The analyzed vibroactuator, supplemented with extended functional capabilities, is established for use in intensifying technological production processes. Full article

Alcohol is widely consumed across cultures and is often used to facilitate relaxation or sleep initiation. This narrative review critically examines evidence published over the past decade (2015–2025) on the effects of alcohol, including wine, on sleep health in community-dwelling adults. Priority was given to systematic reviews and meta-analyses, followed by high-quality observational and experimental studies. Across study designs, evidence consistently shows that although alcohol may reduce sleep onset latency, it disrupts sleep architecture, suppresses rapid eye movement sleep, increases sleep fragmentation, and impairs breathing during sleep, particularly in the second half of the night. Habitual alcohol consumption is associated with poorer subjective sleep quality, insomnia symptoms, and increased risk of sleep-disordered breathing. Mechanistic pathways include effects on neurotransmission, sleep homeostasis, circadian regulation, thermoregulation, and alcohol metabolism during sleep. Evidence also suggests that the timing of alcohol intake and alignment with circadian rhythms may modify these effects, with earlier consumption potentially reducing some adverse outcomes. A brief section addresses the reciprocal relationship, showing that circadian disruption, shift work, and evening chronotype are associated with higher alcohol use. Although wine contains bioactive compounds such as melatonin and polyphenols, current evidence indicates that these components are present at levels insufficient to provide meaningful sleep benefits. Overall, alcohol, including wine, should not be considered a sleep aid, and public health messaging should emphasize dose, timing, and regularity of alcohol consumption in relation to sleep health. Full article

In pellet production, the uniformity of material distribution directly affects the subsequent roasting effect and the quality of finished products. Aiming at the problems of uneven distribution in traditional shuttle distribution systems, such as material stacking at both ends of the wide belt, insufficient parameter matching leading to uneven distribution, and reliance on manual adjustment which makes it difficult to adapt to dynamic working conditions, this paper proposes an intelligent control method based on Integral Simulation and Gradient Descent optimization (IS-GD). Firstly, this method combines the structure and operating parameters of the distribution equipment and accurately simulates the material distribution law on the wide belt during the reciprocating movement of the shuttle through integral technology. Based on the simulation results, longitudinal and lateral uniformity discriminant functions are constructed, and a phased gradient descent optimization strategy is adopted to dynamically adjust the shuttle belt speed, walking speed, and operating parameters of each stage with the goal of minimizing the uniformity index. Experimental results show that this method achieves a significant improvement in lateral distribution uniformity without affecting the stability of longitudinal distribution. This research provides reliable technical support for intelligent distribution control in pellet production and helps to improve the roasting quality and production efficiency of pellets. Full article

Hand rehabilitation in neurologic conditions such as stroke and cerebral palsy traditionally emphasizes repetitive task practice with visually observable feedback, despite motor impairment arising largely from abnormal neuromuscular activation. We present a platform that leverages noninvasive measurements of brain and muscle activity for neurofeedback-guided movement training. Trainees first learn to control EEG during movement preparation, followed by reciprocal control of finger muscle EMG during exoskeleton-assisted movement. We describe the platform design and two feasibility studies. Five neurotypical individuals learned to use EEG and EMG to drive an exoskeleton to grasp and release a virtual ball in a single session. They achieved a mean success rate of 65%, demonstrating improved movement latency (9%) and task completion time (6%) across the session. One individual post-stroke trained with the platform across eight sessions and exhibited improvements on the Box and Blocks Test, the Action Research Arm Test, and the Wolf Motor Function Test. These results demonstrate the feasibility of multi-level, neurofeedback training that targets neural activation throughout movement, rather than movement outcome alone. By explicitly engaging both cortical and muscular control signals, this paradigm offers a promising new direction for hand rehabilitation following neurologic injury. Full article

Steel frame structures have been increasingly widely used in high-rise and multi-story building design. However, traditional rigid welded beam–column joints exhibit poor ductility and high residual stress, which are key reasons for their susceptibility to brittle failure under strong earthquake actions. This study proposes a new type of beam–column joint for steel frames: the corrugated web beam–column joint. In this new joint, the web of the I-beam near the beam flange is partially replaced with a corrugated web that exhibits a folding effect—this modification weakens the plastic bending capacity of the I-beam and promotes the outward movement of plastic hinges. Low-cycle reciprocating loading tests were conducted to verify the performance of two specimens, namely one with the traditional beam–column joint and the other with the corrugated web beam–column joint. Through experimental comparison, it was found that plastic hinges in the new corrugated web joint are generated at the corrugated web, while no damage occurs at the beam-end welds. This indicates that the corrugated web beam–column joint can stably achieve the outward movement of plastic hinges and avoid the location of the beam-end welds, thereby providing theoretical and experimental foundations for the structural design of new ductile steel frames. Full article

Background: Numerical cognition and motor performance rely on overlapping brain systems, yet the extent of their reciprocal interaction remains unclear. This systematic review explores how number processing influences motor execution and how motor activity shapes numerical cognition, emphasizing the neural mechanisms underlying these associations. Methods: A comprehensive search of Scopus, PubMed, MEDLINE, SPORTDiscus, PsycINFO, and SpringerLink, as well as journal citations and conference proceedings (up to August 2025), identified experimental studies examining the interplay between numerical cognition and motor performance in healthy adults. Both randomized and non-randomized designs were included. Two reviewers independently screened, extracted data, and assessed study quality following PRISMA and Cochrane Risk of Bias guidelines. Results: Twelve studies met the inclusion criteria. Most showed that numerical stimuli facilitated motor responses, with congruent number–movement pairings yielding faster reactions and more efficient kinematics. Mental calculation often enhanced motor output (e.g., force, jump height), though interferences emerged under high cognitive load. Conversely, motor actions consistently biased numerical judgments, aligning with spatial–numerical associations. Conclusions: Evidence suggests a predominant pattern of facilitation, likely reflecting shared networks between cognitive and motor resources. These findings advance theoretical understanding and highlight promising translational applications in education, sport, and neurorehabilitation. Full article

The development of endodontics leads to increasingly innovative techniques, which improve mechanical root canal preparation. Endostar E3 Azure (Poldent Co., Warsaw, Poland) is a nickel–titanium file, which can be used in rotary, reciprocal, and optimum torque reverse (OTR) movements. The aim of this study was to assess canal transportation (CT), canal-centering ability (CCA), and wall thickness reduction (WTR) after the use of Endostar E3 Azure files in these three movements. In total, 24 two-canal artificial teeth were used, which were divided into three groups, depending on the applied movement (n = 16 canals). Each canal was initially prepared manually and then instrumented with Endostar E3 Azure files using rotary, reciprocal, or OTR movements. Cone-beam computed tomography was performed before and after canal preparation. The root wall thickness was measured at 3 mm, 6 mm, and 9 mm from the radiological apex and CT, CCA, and WTR were calculated. Reciprocal movement resulted in significantly better outcomes in canal-centering ability (CCA = 0.57) compared with rotary movement (CCA = 0.27) in the middle part of the canal. The wall thickness was significantly reduced in the rotary group: 0.21, 0.19, and 0.13; in the reciprocal group: 0.09, 0.08, and 0.1; and in the OTR group: 0.11, 0.15, and 0.17 at 3, 6, and 9 mm from the apex, respectively. Moreover, rotary movement caused a statistically greater reduction in wall thickness in the apical and middle area compared to other groups. Endostar E3 Azure files significantly reduce the thickness of the root wall along its entire length, which may indicate the effective removal of infected tissue. The use of OTR movement did not affect the analyzed parameters negatively, and it is a safe option which combines the advantageous features of rotary and reciprocal movements. Full article

Background/Objective: Postural stability and motor coordination require precise regulation of agonist and antagonist muscle activities. Jaw clenching modulates neuromuscular control during static and reactive postural tasks. However, its effects on dynamic voluntary movement remain unclear. This pilot study aimed to investigate the effects of jaw clenching on muscle activity and kinematics during repetitive single-leg sit-to-stand task performance. Methods: Eleven healthy adults (age: 21.2 ± 0.4 years; 6 males and 5 females; height: 167.9 ± 9.6 cm; body weight: 59.7 ± 8.1 kg) performed repetitive single-leg sit-to-stand tasks for 30 s under jaw-clenching and control conditions. Electromyography (EMG) signals from eight muscles and kinematic data from 16 inertial measurement unit sensors were analyzed, focusing on the seat-off phase. Results: Jaw clenching resulted in a significantly lower success rate than the control condition (success rate: 0.96 ± 0.13 vs. 0.78 ± 0.29, p = 0.047). Under the jaw clenching condition, failed trials exhibited higher medial gastrocnemius and masseter EMG activity (p < 0.001), lower erector spinae longus EMG activity (p < 0.001), and altered kinematics, including increased trunk yaw and roll angles (p < 0.001). Jaw clenching increased the coactivation of the gastrocnemius and tibialis anterior muscles (p < 0.001), disrupting the reciprocal muscle patterns critical for task performance. Conclusions: These findings suggest that jaw clenching may reduce task performance by altering neuromuscular coordination during dynamic postural tasks. Full article

In this study, a numerical model consisting of high-resolution hydrodynamic and Lagrangian particle tracking modules based on the Finite-Volume Coastal Ocean Model framework was established to simulate the hydrodynamic conditions and characteristics of the sedimentation of aquaculture-derived organic matter (AOM) from cage aquaculture in Sansha Bay. The results showed that Sansha Bay was characterized by regular semidiurnal tides and large tidal ranges. Reciprocating currents with main currents directed northward and southward during the rising and falling tides, respectively, predominated the main channels of the bay. Residual feed had larger settling velocities than feces. The maximal dispersion distances of residual feed and feces during the spring tide were 217.1 and 1805.7 m, respectively, three times those during the neap tide (74.2 and 675.6 m, respectively). During the spring tide, the largest dispersion distance of AOM occurred at the rush moment. The AOM movement trajectories were mainly controlled by the main currents. Both the tidal structure and current characteristics affected the AOM sedimentation in Sansha Bay. The sedimentation characteristics of AOM were unrelated to feeding intensity. The results of simulations agreed with the field observations in this study, suggesting that the estimated model had a good accuracy and sensitivity. Full article

To address the issues of low efficiency, high cost of manual harvesting, and the lack of mechanized harvesting technology and equipment for high-stem Chrysanthemum coronarium, a self-propelled orderly harvester was designed to perform key harvesting operations such as row alignment, clamping and cutting, orderly conveying, and collection. Based on the analysis of agronomic requirements for cultivation and mechanized harvesting needs, the overall structure and working principle of the machine were described. Meanwhile, the key components such as the reciprocating cutting mechanism and orderly conveying mechanism were structurally designed and theoretically analyzed. The main structural and operating parameters of the harvester were determined based on the geometric and kinematic conditions of high-stem Chrysanthemum coronarium during its movement along the conveying path, as well as the mechanical model of the conveying process. In addition, a three-factor, three-level Box-Behnken field experiment was also conducted with the experimental factors including the machine’s forward, cutting, and conveying speed, and evaluation indicators like harvesting loss rate and orderliness. A second-order polynomial regression model was established to analyze the relationship between the evaluation indicators and the factors using the Design-Expert 13 software, which revealed the influence patterns of the machine’s forward speed, reciprocating cutter cutting speed, conveying device speed, and their interaction influence on the evaluation indicators. Moreover, the optimal parameter combination, obtained by solving the optimization model for harvesting loss rate and orderliness, was forward speed of 260 mm/s, cutting speed of 250 mm/s, and conveying speed of 300 mm/s. Field test results showed that the average harvesting loss rate of the prototype was 4.45% and the orderliness was 92.57%, with a relative error of less than 5% compared to the predicted values. The key components of the harvester operated stably, and the machine was capable of performing cutting, orderly conveying, and collection in a single pass. All performance indicators met the mechanized orderly harvesting requirements of high-stem Chrysanthemum coronarium. Full article

Situated at the intersection of social history and psychology, this study examines how early Christian communities in Bithynia-Pontus navigated the persecution narrated in Pliny the Younger’s Epistle X 96. Through systematic textual analysis of Latin and Greek sources—triangulated with comparative evidence from Tacitus and corroborating archaeological data—and interpreted through Conservation-of-Resources and Social Identity theoretical frameworks, we reconstruct the repertoire of collective coping strategies mobilised under Roman repression. Our findings show that ritualised dawn assemblies, mutual economic assistance, and a theologically grounded expectation of post-mortem vindication converted external coercion into internal cohesion; these practices neutralised informer threat, sustained group morale, and ultimately expanded Christian networks across Asia Minor. Moreover, Pliny’s ad hoc judicial improvisations reveal the governor’s own bounded rationality, underscoring the reciprocal nature of stress between the persecutor and persecuted. By mapping the dynamic interaction between imperial policy and subaltern agency, the article clarifies why limited, locally triggered violence consolidated rather than extinguished the nascent movement. The analysis contributes a theoretically informed, evidence-based account of religious-minority resilience, enriching both early Christian historiography and broader debates on group survival under systemic duress. Full article

Aiming at the problem that the whole row of reciprocating seedling picking mechanism is prone to inertial impacts during operation due to its excessive mass, causing seedling damage and positioning errors, this study builds a motion control system with a PLC controller as the core and proposes a composite motion control strategy based on planned S-curve acceleration and deceleration and fuzzy PID to achieve rapid response, precise positioning, and smooth operation of the seedling picking mechanism. By establishing the objective function and constraint conditions and taking into account the dynamic change of the seedling picking displacement, the S-curve acceleration and deceleration control algorithm is planned in six and seven stages to meet the requirements of a smooth transition of the speed and continuous change of the acceleration curve of the seedling picking mechanism during movement. A fuzzy PID positioning control system is designed, the control system transfer function is constructed, and fuzzy rules are formulated to dynamically compensate for the error and its rate of change to meet the requirements of fast response and no overshoot oscillation of the positioning control system. The speed and acceleration of the seedling picking mechanism under the six-segment and seven-segment S-curve acceleration and deceleration motion control conditions were simulated using MATLAB2024a simulation software and compared with the trapezoidal acceleration and deceleration motion control. The planned S-curve acceleration and deceleration control algorithm has a more stable control effect on the seedling picking mechanism when it operates under the conditions of the dynamic change of the displacement, and it meets the design requirements of seedling picking efficiency. The positioning control system was modeled and simulated using the Simulink simulation platform. When KP = 15, KI = 3, and KD = 1, the whole-row seedling picking control system ran stably, responded quickly, and had no overshoot. Compared with the PID control system with fixed parameters, the fuzzy PID control system reduced the time consumption in the rising stage by 24.5% and shortened the overall stabilization process by 17.6%. The zero overshoot characteristic was ensured, and the response speed was faster. When a disturbance signal is added, the overshoot of the fuzzy PID control system is reduced by 2.4%, and the response speed is increased by 6.8% compared with the fixed-parameter PID control system. The dynamic response rate and anti-disturbance performance are better than those of the fixed-parameter PID control system. A bench comparison test was carried out. The results showed that the S-curve acceleration and deceleration motion control algorithm reduced the average mass loss rate of seedlings by 46.19% compared with the trapezoidal acceleration and deceleration motion control algorithm, and the seedling picking efficiency met the design requirements. Fuzzy PID positioning control was used, and the maximum displacement error of the end effector during seedling picking was −1.4 mm, and the average relative error rate was 0.22%, which met the positioning accuracy requirements of the end effector in the X-axis direction and verified the stability and accuracy of the designed control system. The designed control system was tested in the field, and the average comprehensive success rate of seedling picking and throwing reached 96.2%, which verified the feasibility and practicality of the control system. Full article